In a conventional power generation plant, a gas turbine, a steam turbine and so on are used as a power source for power generation.
To obtain much motive force from the turbine, a turbine of specifications of employing working fluid at a temperature equal to or higher than the heat proof temperature of turbine blades has also been developed. In this kind of turbine, for example, coolant is injected and is made to pass through the inside of the turbine blades to cool the turbine blades.
The turbine of the specifications is also constantly required to improve the energy efficiency.